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/* Test whether a file is a symbolic link.
Copyright (C) 2025-2026 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#ifndef _ISSYMLINKAT_H
#define _ISSYMLINKAT_H
/* This file uses _GL_ARG_NONNULL, _GL_INLINE. */
#if !_GL_CONFIG_H_INCLUDED
#error "Please include config.h first."
#endif
#include <errno.h>
#include <unistd.h> /* for readlinkat */
_GL_INLINE_HEADER_BEGIN
#ifndef _GL_ISSYMLINKAT_INLINE
# define _GL_ISSYMLINKAT_INLINE _GL_INLINE
#endif
/* Tests whether FILENAME represents a symbolic link.
This function is more reliable than lstat() / fstatat() followed by S_ISLNK,
because it avoids possible EOVERFLOW errors.
If FILENAME is a relative file name, it is interpreted as relative to the
directory referred to by FD (where FD = AT_FDCWD denotes the current
directory).
Returns
1 if FILENAME is a symbolic link,
0 if FILENAME exists and is not a symbolic link,
-1 with errno set if determination failed, in particular
-1 with errno = ENOENT or ENOTDIR if FILENAME does not exist. */
#ifdef __cplusplus
extern "C" {
#endif
_GL_ISSYMLINKAT_INLINE int issymlinkat (int fd, const char *filename)
_GL_ARG_NONNULL ((2));
_GL_ISSYMLINKAT_INLINE int
issymlinkat (int fd, const char *filename)
{
char linkbuf[1];
if (readlinkat (fd, filename, linkbuf, sizeof (linkbuf)) >= 0)
return 1;
if (errno == EINVAL)
return 0;
else
return -1;
}
#ifdef __cplusplus
}
#endif
_GL_INLINE_HEADER_END
#endif /* _ISSYMLINKAT_H */
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